This invention relates generally to a dental model base assembly and more particularly to such an assembly in which a dental base body having a plurality of apertures may be attached to a disposable dental articulator or a metal articulator.
Damaged teeth may be repaired or replaced by crowns, bridge inlays or other common dental prosthesis. A successful repair requires accurate alignment and visual uniformity of the repaired tooth with the patient""s other teeth. Typically, a model is made of the patient""s teeth and the prosthesis is fitted to the model and adjusted to achieve proper alignment and visual uniformity.
The model is typically formed by having a patient bite into a pliant casting material which cures to create a mold cavity having a negative impression of the patient""teeth and gums. The mold can be of all or any portion of the patient""gum line. A castable material is then poured into the negative impression to create a stone replica or dental model of the patient""s teeth and gums.
To facilitate prosthesis development, the replica of the damaged tooth or teeth is severed from the remainder of the dental model. Severability is achieved by positioning the knurled end of a tapered dowel pin in the uncured stone material in correspondence with the damaged tooth or teeth. The dowel pin or pins must be carefully aligned and held in position which requires skill and time. Once the casting of the gum and teeth has hardened, the cured dental model is positioned adjacent an uncured dental model base which is held in a dental base mold. The tapered portion of the dowel pins protruding from the dental model are positioned in the uncured dental model base. To prevent bonding with the dental model base, wax may be placed between the base and the dental model and around the tapered portion of the dowel pins.
Once the dental model base has cured a saw cut on each side of the damaged tooth model is made down to the dental model base which allows removal of the damaged tooth model and the attached dowel from the rest of the dental model.
Once the damaged tooth model is removed, the prosthesis can be fitted and adjusted without the spatial limitations encountered when the damaged tooth model is joined to the full dental model. After the prosthesis is made and attached to the dental model segment, the tapered dowel attached to the dental model segment is guided into its respective aperture in the dental model base which guides the dental model segment to its position in the dental model. Alignment and visual conformity are then assessed.
Alignment is ascertained by evaluating the registration of the repaired tooth with the dental model of the patient""s opposing teeth. This is achieved by connecting the upper and lower dental model with an articulator. If the prosthesis is out of alignment or does not visually conform to the rest of the patient""s teeth, the dental model segment containing the damaged tooth can be removed adjusted and returned to the dental model base. This process is repeated until proper alignment and visual conformity is achieved. Thus, the model of the damaged tooth may be removed and inserted into the base repeatedly. This repeated removal and reinsertion can damage the fit of the tapered portion of the dowel pin within the cast dental model base which decreases the accuracy of the alignment procedure.
The Vertex(copyright) articulator is one disposable articulator typically used to check the alignment of repaired teeth. The Vertex(copyright) articulator is glued to a slot in the rear portion of the cast dental model bases. Other typical articulators are metal and the dental model is attached semi-permanently by applying a bonding agent, such as plaster, to the dental model base and the articulator. While metal articulators may be separated at the hinge, protruding portions of the articulator obstruct access to the dental model from certain directions. A technician may prefer using one type of articulator in certain circumstances and the other when circumstances are different.
The above described process requires time for the dental model and dental model base castings to cure. Also, skill and time are both required to accurately place the dowel pins in the dental model. Any misalignment may result in an unusable casting. Thus, considerable time is spent achieving proper alignment and allowing the dental model base casting to cure.
Some dental model bases are fabricated from plastic. In one version, a technician must drill a tapered aperture in the dental model base to accommodate the placement of the dowel pin in the dental model casting. Skill and time are required to align the dowel pin with the damaged tooth model and the plastic base and to accurately drill the tapered aperture which receives the tapered dowel pin. Another available plastic dental model base has a plurality of pre-formed apertures for receiving dowel pins which eliminate the above-mentioned drilling step. However, the apertures are not positioned to correspond with normal tooth placement.
Also, in some existing full arch plastic bases, plastic extends from the right molars to the left molars, creating a platform for excess casting material in the lingual area. It may be desirable to remove this excess casting material as part of the model preparation process. The plastic platform interferes with this removal step. The platform also may hinder assessment of visual conformity.
In summary, the dowel pins may be accurately aligned with the damaged tooth in a cast dental model base; however, the casting procedure takes time and requires skill. Plastic bases avoid the expense of casting a dental model base but may require additional steps, such as drilling, for accurate placement of a dowel within the dental model. If the plastic base has preformed apertures for dowel placement, the apertures often do not correspond to normal tooth placement and skill is required to accurately place the dowels within the dental model. Inaccurate placement of the dowel in a cast or preformed dental model base may result in an unusable dental model as the dental model segment may be unseverable from the dental model.
As mentioned above, brass dowels or pins are typically used to detachably engage a dental model segment to the dental model base. However, brass dowels are undesirable in some circumstances. For example, porcelain facings are often created to repair damaged teeth. The green porcelain material is applied to a damaged tooth model and the dental model segment containing the tooth model is heated to set the porcelain material. This heating temperature is elevated and will adversely affect typical metal dowels.
U.S. Pat. No. 5,788,489 addresses many of the concerns raised above, and is incorporated herein by reference.
The inventions claimed herein are directed to improvements to prior art dental model bases.
One embodiment has a dental model mounting surface. A wall extends from the second side of the dental model mounting surface. The interior surface of the wall defines a cavity. A plurality of projections extend from the second side of the dental model mounting surface into the cavity.
The projections define a plurality of tapered apertures extending from the first side of the dental model mounting surface.
In another embodiment, a single projection extends into the cavity described above. The projection defines a plurality of tapered apertures extending from the dental model support surface described above.